1. Field of the Invention
This invention relates to patterns on a transparent substrate, e.g. a glass substrate to increase light transmission and/or light trapping, and more particularly, to patterns on a glass cover plate of a solar cell to convert s-polarized light wave to p-polarized light wave to increase transmission of light waves through the cover plate, and/or to trap internally reflected light waves, to increase electrical output of the solar cell.
2. Discussion of the Present Technology
At the present time solar cells include a transparent cover plate, e.g. a glass cover plate over a mono-crystalline silicon photovoltaic module. The cover plate protects the module against a hostile environment, e.g. rain, snow, and wind blown debris, e.g. wind blown dust and stones, while passing solar energy through the cover plate to the module. Although the use of transparent cover plates is acceptable, there are limitations. More particularly and with exception, the solar energy is incident on the glass cover plate as non-polarized collimated light waves. As is appreciated by those skilled in the art, when the non-polarized light waves are incident on the outer surface of the glass cover plate at a Brewster-angle the non-polarized light waves become polarized light waves with the p-polarized light waves having an electric field parallel to the plane of incidence passing thought the glass cover plate, and the s-polarized light waves having an electric field perpendicular to the plane of incidence partly reflected away from the glass cover plate and the photovoltaic module.
Technology is available, e.g. as disclosed in U.S. Pat. Nos. 4,913,520; 5,559,634; 5,594,830 and 5,640,480 to convert s-polarized light waves reflected from a glass cover plate to p-polarized light waves (hereinafter also referred to as “converted p-polarized light waves”) and pass the p-polarized light waves and the converted p-polarized light waves through the glass cover plate to increase the light transmission through the cover plate. A drawback of the presently available technology, e.g. as disclosed in the above-mentioned patents, is that the light source is stationary and the light waves travel along a set, unchanging path, such that the light waves are always incident on the surface of the glass substrate at the Brewster-angle, and the s-polarized light waves are converted to p-polarized light waves. In the case of solar cells, the light source is the sun, and the sun travels along a path such that the sun's rays are not always incident on the glass cover plate at the Brewster-angle. Tracking equipment is available to move the solar cell to have the glass cover plate track the movement of the sun such that the sun's rays are incident on the cover plate at the Brewster-angle. However, as is appreciated by those skilled in the art, tracking equipment is expensive and must be maintained in proper operating condition.
Another limitation associated with transmitting light waves through a glass cover plate is the loss of light waves that are re-reflected through the glass cover plate. More particularly, the light waves are incident on a first surface of the glass cover plate, and a portion of the light waves incident on the first surface passes through the first surface into the body of the glass cover plate and a portion of the light is reflected toward an opposite second surface of the glass cover plate. At the opposite second surface of the glass cover plate, a portion of the light waves passes through the second surface, and a portion of the light waves is reflected back toward and through the first surface of the glass cover plate.
As can now be appreciated, it would be advantageous to provide a transparent plate or substrate, for example, but not limited to a display cover and/or a cover plate for a solar absorbing device, for example, but not limited to a solar cell, that minimizes, if not eliminates, the limitations of the presently available cover plates by increasing solar light transmission through the transparent plate, for example, but not limited to a display cover and/or a cover plate of a solar cell.